U.S. Pat. No. 4,520,950 discloses an in-home drink dispenser which include a source of concentrate, e.g., syrup, a carbonator which is filled with ice and water and a carbon dioxide tank for supplying carbon-dioxide to carbonate the water in the tank. In such an in-home drink dispenser, it is, of course, important to know how much carbonated water is left and also how much carbon dioxide is left. Knowing when one is about to run out of carbon dioxide is of great importance, particularly where a cylinder is not immediately on hand. The carbonator can be refilled with water and ice; however, if one runs out of carbon dioxide, at a time when the supplier is not open for business, it may be necessary to wait, possibly over a weekend, to get a new cylinder. Thus, the need for an indication of this level is particularly important.
Furthermore, in regard to the carbon dioxide cylinders, since the cylinders are being handled by people not used to such, there is a need to take measures to protect the cylinders and to provide for ease of use, as well as ease of insertion and removal of the cylinder from the drink dispenser.